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LT6700-1/LT6700-2/LT6700-3 Micropower, Low Voltage, SOT-23, Dual Comparator with 400mV Reference
FEATURES
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DESCRIPTIO
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Low Quiescent Current: 6.5A Typ at 5V Wide Supply Range: 1.4V to 18V 400mV Reference 2% Accuracy Over Temperature Input Range Includes Ground Over-The-Top(R) Input Range Over-The-Top Open-Collector Outputs Internal Hysteresis: 6.5mV Typ Low Input Bias Current: 10nA Max 40mA Typical Output Sink Current Supports Wired-AND Connections Choice of Input Polarities: LT6700-1/LT6700-2/ LT6700-3 Low Profile (1mm) SOT-23 (ThinSOTTM) Package
The LT(R)6700-1/LT6700-2/LT6700-3 combine two micropower, low voltage comparators with a 400mV reference in the 6-lead SOT-23 package. Operating with supplies from 1.4V up to 18V, the devices draw only 6.5A typical, making them ideal for low voltage system monitoring. Hysteresis is included in the comparators, easing design requirements to insure stable output operation. The comparators each have one input available externally, the other inputs are connected internally to the reference. The comparator outputs are open collector and the output load can be referred to any voltage up to 18V, independent of supply voltage. The output stage sinking capability is guaranteed greater than 5mA over temperature. The three versions of the part differ by the polarity of the available comparator inputs. The LT6700-1 has one inverting input and one noninverting input, making it suitable for use as a window comparator. The LT6700-2 has two inverting inputs and the LT6700-3 has two noninverting inputs. All versions are offered in commercial, industrial and automotive temperature ranges.
, LTC and LT are registered trademarks of Linear Technology Corporation. Over-The-Top is a registered trademark of Linear Technology. ThinSOT is a trademark of Linear Technology Corporation.
APPLICATIO S
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Battery-Powered System Monitoring Threshold Detectors Window Comparators Relay Driving Optoisolator Driving Industrial Control Systems Handheld Instruments
TYPICAL APPLICATIO
LT6700-3 4
Micropower Battery Monitor
VBATT 1.4V (MIN) 3V (NOM) 5 1M 1M COMP B VBATT > 1.6V 1M 406 404
+ -
THRESHOLD VOLTAGE (mV)
6 63.4k
402 400 398 396 394 TWO TYPICAL PARTS 392 COMP A AND B VS = 5V 390 -60 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
6700123 TA02
ALKALINE AA CELLS
+ +
VR = 400mV REFERENCE COMP A
VS
-
3 261k
1
VBATT > 2V MONITOR CONSUMES ~10A HYSTERESIS IS APPROXIMATELY 2% OF TRIP VOLTAGE
+
0.1F 2
6700123 TA01
U
Comparator Thresholds vs Temperature
#1A #1B #2A #2B RISING INPUT FALLING INPUT
U
U
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1
LT6700-1/LT6700-2/LT6700-3
ABSOLUTE
AXI U
RATI GS (Note 1)
Specified Temperature Range (Note 5) LT6700CS6-1/-2/-3 ............................ - 40C to 85C LT6700IS6-1/-2/-3 ............................. - 40C to 85C LT6700HS6-1/-2/-3 .......................... - 40C to 125C Maximum Junction Temperature ......................... 150C Storage Temperature Range ................... - 65C to 150 Lead Temperature (Soldering, 10 sec).................. 300C
Total Supply Voltage (VS to GND) ........................ 18.5V Input Voltage (+IN, -IN) (Note 3) ..................................... 18.5V to (GND - 0.3V) Output Voltage (OUT) ................ 18.5V to (GND - 0.3V) Output Short-Circuit Duration (Note 2) ........... Indefinite Input Current (Note 3) ....................................... -10mA Operating Temperature Range (Note 4) LT6700CS6-1/-2/-3 ............................ - 40C to 85C LT6700IS6-1/-2/-3 ............................. - 40C to 85C LT6700HS6-1/-2/-3 .......................... - 40C to 125C
PACKAGE/ORDER I FOR ATIO
TOP VIEW OUTA 1 GND 2 +INA 3 6 OUTB 5 VS 4 -INB OUTA 1 GND 2 -INA 3
S6 PACKAGE 6-LEAD PLASTIC TSOT-23 TJMAX = 150C, JA = 230C/W
S6 PACKAGE 6-LEAD PLASTIC TSOT-23 TJMAX = 150C, JA = 230C/W
ORDER PART NUMBER LT6700CS6-1 LT6700IS6-1 LT6700HS6-1
S6 PART MARKING* LTK7
ORDER PART NUMBER LT6700CS6-2 LT6700IS6-2 LT6700HS6-2
*The temperature grades are identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL VTH(R) PARAMETER Rising Input Threshold Voltage
TA = 25C, unless otherwise specified.
MIN 394 395 393 392 386 387 385 384 3.5 TYP 400 400 400 400 393.5 393.5 393.5 393.5 6.5 MAX 406 405 407 408 401 400 402 403 9.5 UNITS mV mV mV mV mV mV mV mV mV
CONDITIONS RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing
VTH(F)
Falling Input Threshold Voltage
HYS
HYS = VTH(R) - VTH(F)
2
U
U
W
WW
U
W
TOP VIEW 6 OUTB 5 VS 4 -INB OUTA 1 GND 2 +INA 3
TOP VIEW 6 OUTB 5 VS 4 +INB
S6 PACKAGE 6-LEAD PLASTIC TSOT-23 TJMAX = 150C, JA = 230C/W
S6 PART MARKING* LTADL
ORDER PART NUMBER LT6700CS6-3 LT6700IS6-3 LT6700HS6-3
S6 PART MARKING* LTADM
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LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
SYMBOL IB PARAMETER Input Bias Current
TA = 25C, unless otherwise specified.
MIN TYP 0.01 0.01 4 55 60 70 0.01 0.01 29 18 2.2 0.22 MAX 10 10 10 200 200 200 0.8 0.8 UNITS nA nA nA mV mV mV A A s s s s
CONDITIONS VS = 1.4V, 18V, VIN = VS VS = 1.4V, VIN = 18V VS = 1.4V, 18V, VIN = 0.1V 10mV Input Overdrive VS = 1.4V, IOUT = 0.5mA VS = 1.6V, IOUT = 3mA VS = 5V, IOUT = 5mA VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive VS = 5V, 10mV Input Overdrive, RL = 10k, VOL = 400mV VS = 5V, 10mV Input Overdrive, RL = 10k, VOH = 0.9 * VS VS = 5V, 10mV Input Overdrive, RL = 10k VO = (0.1 to 0.9) * VS VS = 5V, 10mV Input Overdrive, RL = 10k VO = (0.1 to 0.9) * VS No Load Current VS = 1.4V VS = 5V VS = 12V VS = 18V
VOL
Output Low Voltage
IOFF tPD(HL) tPD(LH) tr tf IS
Output Leakage Current High-to-Low Propagation Delay Low-to-High Propagation Delay Output Rise Time Output Fall Time Supply Current
5.7 6.5 6.9 7.1
10.0 11.0 12.5 13.0
A A A A
The q denotes the specifications which apply over the temperature range of 0C TA 70C, unless otherwise specified (Notes 4, 5).
SYMBOL VTH(R) PARAMETER Rising Input Threshold Voltage CONDITIONS RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V VS = 1.4V, 18V, VIN = VS VS = 1.4V, VIN = 18V VS = 1.4V, 18V, VIN = 0.1V 10mV Input Overdrive VS = 1.4V, IOUT = 0.5mA VS = 1.6V, IOUT = 3mA VS = 5V, IOUT = 5mA VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive No Load Current VS = 1.4V VS = 5V VS = 12V VS = 18V
q q q q q q q q
MIN 391.0 392.5 390.0 389.0 383.5 384.5 382.5 381.5 3
TYP
MAX 409.0 407.5 410.0 411.0 403.5 402.5 404.5 405.5 11 15 15 15 250 250 250 1 1 13.0 14.0 15.5 16.0
UNITS mV mV mV mV mV mV mV mV mV nA nA nA mV mV mV A A A A A A
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VTH(F)
Falling Input Threshold Voltage
HYS IB
HYS = VTH(R) - VTH(F) Input Bias Current
VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing q
q q q q q q q q q q q q
VOL
Output Low Voltage
IOFF IS
Output Leakage Current Supply Current
3
LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
SYMBOL VTH(R) PARAMETER Rising Input Threshold Voltage
The q denotes the specifications which apply over the temperature range of -40C TA 85C, unless otherwise specified (Notes 4, 5).
CONDITIONS RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing VS = 1.4V, 18V, VIN = VS VS = 1.4V, VIN = 18V VS = 1.4V, 18V, VIN = 0.1V 10mV Input Overdrive VS = 1.4V, IOUT = 0.1mA VS = 1.6V, IOUT = 3mA VS = 5V, IOUT = 5mA VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive VS = 1.4V, VOUT = 18V, VIN = 40mV Overdrive No Load Current VS = 1.4V VS = 5V VS = 12V VS = 18V MIN
q q q q q q q q q q q q q q q q q q q q q
TYP
MAX 410 408 411 412 404.5 403.5 405.5 406.5 11.5 15 15 15 250 250 250 1 1 14.0 15.0 16.5 17.0
UNITS mV mV mV mV mV mV mV mV mV nA nA nA mV mV mV A A A A A A
390 392 389 388 382.5 383.5 381.5 380.5 2
VTH(F)
Falling Input Threshold Voltage
HYS IB
HYS = VTH(R) - VTH(F) Input Bias Current
VOL
Output Low Voltage
IOFF IS
Output Leakage Current Supply Current
The q denotes the specifications which apply over the temperature range of -40C TA 125C, unless otherwise specified (Notes 4, 5).
SYMBOL VTH(R) PARAMETER Rising Input Threshold Voltage CONDITIONS RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V RL = 100k, VO = 2V Swing VS = 1.4V VS = 5V VS = 12V VS = 18V VS = 1.4V, 5V, 12V, 18V, RL = 100k, VO = 2V Swing VS = 1.4V, 18V, VIN = VS VS = 1.4V, VIN = 18V VS = 1.4V, 18V, VIN = 100mV 10mV Input Overdrive VS = 1.4V, IOUT = 0.1mA VS = 1.6V, IOUT = 3mA VS = 5V, IOUT = 5mA VS = 1.4V, 18V, VOUT = VS, VIN = 40mV Overdrive VS = 1.4V, VOUT = VS, VIN = 40mV Overdrive No Load Current VS = 1.4V VS = 5V VS = 12V VS = 18V MIN
q q q q q q q q q q q q q q q q q q q q q
LT6700H TYP
MAX 411 410 412 413 405.5 404.5 406.5 407.5 13.5 45 45 50 250 250 250 1 1 16.0 17.0 18.5 19.0
UNITS mV mV mV mV mV mV mV mV mV nA nA nA mV mV mV A A A A A A
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390 392 389 388 381.5 382.5 380.5 379.5 2
VTH(F)
Falling Input Threshold Voltage
HYS IB
HYS = VTH(R) - VTH(F) Input Bias Current
VOL
Output Low Voltage
IOFF IS
Output Leakage Current Supply Current
4
LT6700-1/LT6700-2/LT6700-3
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those beyond which the life of the device may be impaired. Note 2: A heat sink may be required to keep the junction temperature below the absolute maximum rating when the output is shorted indefinitely. Note 3: The inputs are protected by ESD diodes to the ground. If the input voltage exceeds -0.3V below ground, the input current should be limited to less than 10mA. Note 4: The LT6700CS6-1/-2/-3 and LT6700IS6-1/-2/-3 are guaranteed functional over the operating temperature range of - 40C to 85C. The LT6700HS6-1/-2/-3 are guaranteed functional over the operating temperature range of -40C to 125C. Note 5: The LT6700CS6-1/-2/-3 are guaranteed to meet the specified performance from 0C to 70C. The LT6700CS6-1/-2/-3 are designed, characterized and expected to meet specified performance from - 40C to 85C but are not tested or QA sampled at these temperatures. The LT6700IS6-1/-2/-3 are guaranteed to meet specified performance from -40C to 85C. The LT6700HS6-1/-2/-3 are guaranteed to meet specified performance from -40C to 125C.
PI FU CTIO S
VS LT6700-1 -INB 4 5 COMP B 6 OUTB LT6700-2 -INB 4 VS 5 COMP B 6 OUTB LT6700-3 +INB 4 VS 5 COMP B 6 OUTB
- +
400mV REFERENCE COMP A
-
+INA 3
+
2 GND
6700123 PF01
OUTA (Pin 1): Open-Collector Output of Comparator Section A. This pin provides drive for up to 40mA of load current. Off-state voltage may be as high as 18V above GND (Pin 2), regardless of VS used. GND (Pin 2): Ground. This pin is also the low side return of the internal 400mV reference. INA (Pin 3): External Input for Comparator Section A. The voltage on this pin can range from -0.3V to 18V with respect to GND (Pin 2) regardless of VS used. The input is noninverting for the LT6700-1 and LT6700-3, and inverting for the LT6700-2. The other section A comparator input is internally connected to the 400mV reference.
U
U
U
- +
+ -
VS
400mV REFERENCE COMP A
VS
400mV REFERENCE COMP A
VS
+
1 OUTA -INA 3
-
1 OUTA +INA 3
1 OUTA
-
2 GND
6700123 PF02
+
2 GND
6700123 PF03
INB (Pin 4): External Input for Comparator Section B. The voltage on this pin can range from -0.3V to 18V with respect to GND (Pin 2) regardless of VS used. The input is noninverting for the LT6700-3, and inverting for the LT6700-1 and LT6700-2. The other section B comparator input is internally connected to the 400mV reference. VS (Pin 5): Comparator Core Supply Voltage. The parts are characterized for operation with 1.4V VS 18V with respect to GND (Pin 2). OUTB (Pin 6): Open-Collector Output of Comparator Section B. This pin provides drive for up to 40mA of load current. Off-state voltage may be as high as 18V above GND (Pin 2), regardless of VS used.
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5
LT6700-1/LT6700-2/LT6700-3 TYPICAL PERFOR A CE CHARACTERISTICS
Distribution of Rising Input Threshold Voltage
18 16 VS = 5V TA = 25C 18 16
PERCENT OF UNITS (%)
PERCENT OF UNITS (%)
PERCENT OF UNITS (%)
14 12 10 8 6 4 2 0 394 396 398 400 402 404 406 RISING INPUT THRESHOLD VOLTAGE (mV)
6700123 G01
Rising Input Threshold Voltage vs Temperature
RISING INPUT THRESHOLD VOLTAGE (mV) RISING INPUT THRESHOLD VOLTAGE (mV)
403 402 401 400 399 398 397
#1 #2
402.5 402.0 401.5 401.0 400.5 400.0 399.5
RISING INPUT THRESHOLD VOLTAGE (mV)
404
FOUR TYPICAL PARTS VS = 5V
#3
#4
396 -60 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
6700123 G04
Hysteresis vs Temperature
10 FOUR TYPICAL PARTS 9 VS = 5V #1 #2 8 #3 #4 7 6 5 4 3 2 -60 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
6700123 G07
HYSTERESIS (mV)
HYSTERESIS (mV)
7 6 5 4 3 2 -60 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
6700123 G08
HYSTERESIS (mV)
6
UW
Distribution of Falling Input Threshold Voltage
VS = 5V TA = 25C 20 18 16 14 12 10 8 6 4 2 0
Distribution of Hysteresis
VS = 5V TA = 25C
14 12 10 8 6 4 2 0 388 390 392 394 396 398 400 FALLING INPUT THRESHOLD VOLTAGE (mV)
6700123 G02
4
4.8
5.6 6.4 7.2 HYSTERESIS (mV)
8
8.8
6700123 G03
Rising Input Threshold Voltage vs Temperature
403.0 VS = 1.4V VS = 5V VS = 12V VS = 18V 403.0 402.5 402.0 401.5 401.0 400.5 400.0 399.5 399.0
Rising Input Threshold Voltage vs Supply Voltage
TA = 25C TA = 85C TA = 125C TA = -55C
399.0 -60 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
6700123 G05
2
4
8 10 12 14 6 SUPPLY VOLTAGE (V)
16
18
6700123 G06
Hysteresis vs Temperature
10 9 8 VS = 1.4V VS = 5V VS = 12V VS = 18V 10 9 8 7 6 5 4 3 2
Hysteresis vs Supply Voltage
TA = 25C TA = 85C TA = 125C TA = -55C
2
4
8 10 12 14 6 SUPPLY VOLTAGE (V)
16
18
6700123 G09
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LT6700-1/LT6700-2/LT6700-3 TYPICAL PERFOR A CE CHARACTERISTICS
Minimum Supply Voltage
1 0
THRESHOLD SHIFT (mV) 10
-1 -2 -3 -4 -5 0.9 TA = 25C TA = 85C TA = 125C TA = -55C 1.1 1.5 1.3 1.7 SUPPLY VOLTAGE (V) 1.9
6700123 G10
SUPPLY CURRENT (A)
8 7 6 5 4 1.4 3.4 5.4 7.4 9.4 11.4 13.4 15.4 17.4 SUPPLY VOLTAGE (V)
6700123 G11
SUPPLY CURRENT (A)
Supply Current vs Output Sink Current
1000 TA = -40C VS = 1.4V VS = 5V VS = 12V VS = 18V 1000
SUPPLY CURRENT (A)
SUPPLY CURRENT (A)
100
100
SUPPLY CURRENT (A)
10
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
Below Ground Input Bias Current
10000 VS = 18V -0.3V < VIB < 0V TA = 25C TA = 85C TA = 125C TA = -55C
3
INPUT BIAS CURRENT (nA)
INPUT BIAS CURRENT (nA)
1000
INPUT BIAS CURRENT (nA)
100
10
1 -0.3
CURRENT IS GOING OUT OF THE DEVICE
-7
-0.2 -0.1 INPUT VOLTAGE (V)
UW
6700123 G13
Quiescent Supply Current vs Supply Voltage
TA = 25C TA = 85C TA = 125C TA = -55C
Start-Up Supply Current
50 TA = 25C TA = 85C TA = 125C TA = -55C
9 NO LOAD CURRENT
40
30
20
10
0
0
0.2
0.4 0.6 0.8 1.0 1.2 SUPPLY VOLTAGE (V)
1.4
6700123 G12
Supply Current vs Output Sink Current
TA = 25C VS = 1.4V VS = 5V VS = 12V VS = 18V
Supply Current vs Output Sink Current
1000 TA = 85C VS = 1.4V VS = 5V VS = 12V VS = 18V
100
10
10
100
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
100
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
100
6700123 G14
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Low Level Input Bias Current
CURRENT IS POSITIVE GOING 2 INTO THE DEVICE 1 0 -1 -2 -3 -4 -5 -6 VS = 18V 0V < VIB < 1V TA = 25C TA = 85C TA = 125C TA = -55C 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 INPUT VOLTAGE (V) 1
10
High Level Input Bias Current
CURRENT IS GOING INTO THE DEVICE
1
0.1
0
6700123 G16
VS = 18V 0.01 VIB > 1V TA = 25C TA = 85C TA = 125C 0.001 1 3 5 7 9 11 13 INPUT VOLTAGE (V)
15
17
6700123 G17
6700123 G18
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LT6700-1/LT6700-2/LT6700-3 TYPICAL PERFOR A CE CHARACTERISTICS
Output Saturation Voltage vs Output Sink Current
1000
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (mV)
100
100
OUTPUT SATURATION VOLTAGE (mV)
TA = -40C VS = 1.4V VS = 5V VS = 12V VS = 18V
10
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
Output Short-Circuit Current
80
SHORT-CIRCUIT CURRENT (mA)
OUTPUT LEAKAGE CURRENT (nA)
SHORT-CIRCUIT CURRENT (mA)
70 60 50 40 30 20 10 0 0 2 4 VS = 5V TA = 25C TA = 85C TA = 125C TA = -55C 8 10 12 14 6 OUTPUT VOLTAGE (V) 16 18
Propagation Delay vs Input Overdrive
60 50
PROPAGATION DELAY (s)
TA = 25C
RISE AND FALL TIME (s)
LH NONINV HL NONINV LH INV HL INV
40 30 20 10 0
0
20
60 80 40 INPUT OVERDRIVE (mV)
8
UW
6700123 G19
6700123 G22
Output Saturation Voltage vs Output Sink Current
1000 TA = 25C VS = 1.4V VS = 5V VS = 12V VS = 18V 1000
Output Saturation Voltage vs Output Sink Current
TA = 85C VS = 1.4V VS = 5V VS = 12V VS = 18V
100
10
10
100
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
100
1 0.001
0.01 0.1 1 10 OUTPUT SINK CURRENT (mA)
100
6700123 G20
6700123 G21
Output Short-Circuit Current
80 70 60 50 40 30 20 10 0 0 2 4 8 10 12 14 6 OUTPUT VOLTAGE (V) 16 18 TA = 25C VS = 1.4V VS = 5V VS = 12V VS = 18V 10
Output Leakage Current
1
0.1
0.01
VS = 5V TA = 25C TA = 85C TA = 125C TA = -55C
0.001 0 2 4 6 8 10 12 14 OUTPUT VOLTAGE (V) 16 18
6700123 G23
6700123 G24
Rise and Fall Times vs Output Pull-Up Resistor
100 VS = 5V CL = 20pF TA = 25C RISE 1 FALL
VIN 10mV/DIV AC VO(NINV) 5V/DIV DC VO(INV) 5V/DIV DC
Noninverting and Inverting Comparators' Propagation Delay
10
0.1
100
6700123 G25
0.01 0.1
1 10 100 OUTPUT PULL-UP RESISTOR (k)
1000
20s/DIV VS = 5V TA = 25C RLOAD = 10k CONNECTED TO VS VIN(OVERDRIVE) = 10mV OVER THE INPUT VOLTAGE THRESHOLDS
67000123 G27
6700123 G26
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LT6700-1/LT6700-2/LT6700-3
APPLICATIO S I FOR ATIO
The LT6700-1/LT6700-2/LT6700-3 devices are a family of dual micropower comparators with a built-in 400mV reference. Features include wide supply voltage range (1.4V to 18V), Over-The-Top input and output range, 2% accurate rising input threshold voltage and 6.5mV typical builtin hysteresis. The comparator's open-collector outputs can sink up to 40mA typical. Internal Reference Each of the comparator sections has one input available externally, with the three versions of the part differing by the polarity of those available inputs (i.e., inverting or noninverting). The other comparator inputs are connected internally to the 400mV reference. The rising input threshold voltage of the comparators is designed to be equal to that of the reference (i.e., 400mV). The reference voltage is established with respect to the device GND connection. Hysteresis Each comparator has built-in 6.5mV (typical) hysteresis to simplify designs, insure stable operation in the presence of noise at the inputs, and to reject supply rail noise that might be induced by state change load transients. The hysteresis is designed such that the falling input threshold voltage is nominally 393.5mV. External positive feedback circuitry can be employed with noninverting comparator inputs to increase effective hysteresis if desired, but such circuitry will provide an apparent effect on both the rising and falling input thresholds (the actual internal thresholds remain unaffected). Comparator Inputs A comparator input can swing from ground to 18V, regardless of the supply voltage used. The typical input current for inputs well above threshold (i.e., >800mV) is a few pA leaking into an input. With decreasing input voltage, a small bias current begins to be drawn out of the input, reaching a few nA when at ground potential. The input may be forced 100mV below ground without causing an improper output, though some additional bias current will begin to flow from the parasitic ESD input protection diode. Inputs driven further negative than 100mV below ground will not cause comparator malfunction or damage
U
(provided the current is limited to 10mA), but the accuracy of the reference cannot be guaranteed, in which case the output state of the alternate comparator may be effected. Comparator Outputs The comparator outputs are open collector and capable of sinking 40mA typical. Load currents are directed out the GND pin of the part. The output off-state voltage may range between -0.3V and 18V with respect to ground, regardless of the supply voltage used. As with any open-collector device, the outputs may be tied together to implement wire-AND logic functions. Power Supplies The comparator family core circuitry operates from a single 1.4V to 18V supply. A minimum 0.1F bypass capacitor is required between the VS pin and GND. When an output load is connected to the supply rail near the part and the output is sinking more than 5mA, a 1F bypass capacitor is recommended. In instances where the supply is relatively "soft" (such as with small batteries) and susceptible to load steps, an additional 47 series decoupling resistor can further improve isolation of supply transients from the VS pin. Flexible Window Comparator Using the LT6700-1 as shown in the circuits of Figure 1, the wire-AND configuration permits high accuracy window functions to be implemented with a simple 3-resistor voltage divider network. The section A comparator provides the VL trip-point and the section B comparator provides the VH trip-point, with the built-in hysteresis providing about 1.7% recovery level at each trip point to prevent output chatter. For designs that are to be optimized to detect departure from a window limit, the nominal resistor divider values are selected as follows (refer to the resistor designators shown on the first circuit of Figure 1): R1 400k (this sets the divider current >> IB of inputs) R2 = R1 * (0.98 * VH/VL - 1) R3 = R1 * (2.5 * VH - 0.98 * VH/VL)
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W
UU
9
LT6700-1/LT6700-2/LT6700-3
APPLICATIO S I FOR ATIO
3.3V Supply Monitor
3.3V
R3 301k
5 VS 1 3 +INA OUTA LT6700-1 -INB OUTB GND 2 6
VOUT 33k VS VOUT HIGH = (3.1V < VS < 3.5V) 0.1F HYSTERESIS ZONES APPROXIMATELY 2% OF TRIP VOLTAGE
R2 6.04k 4 R1 40.2k
Figure 1. Simple Window Comparator
To create window functions optimized for detecting entry into a window (i.e. where the output is to indicate a "coming into spec" condition, as with the examples in Figure 1), the nominal resistor values are selected as follows: R1 400k (this sets the divider current >> IB of inputs) R2 = R1 * (1.02 * VH/VL - 1) R3 = R1 * (2.54 * VH - 1.02 * VH/VL) The worst-case variance of the trip-points is related to the specified threshold limits of the LT6700 device and the basic tolerance of divider resistors used. For resistor tolerance RTOL (e.g. 0.01 for 1%), the worst-case trippoint voltage (either VH or VL) deviations can be predicted as follows (italicized values are taken from the datasheet, expressed in volts): Max dev VTRIP = VTRIPnom * {2 * RTOL * [(VTRIPnom - 0.4) / VTRIPnom] + 1.25 * (VTH(R)max - VTH(R)min)} Max dev VTRIP = VTRIPnom * {2 * RTOL * [(VTRIPnom - 0.39) / VTRIPnom] + 1.27 * (VTH(F)max - VTH(F)min)} Generating an External Reference Signal In some applications, it would be advantageous to have access to a signal that is directly related to the internal 400mV reference, even though the reference itself is not available externally. This can be accomplished to a reasonable degree by using an inverting comparator section as a "bang-bang" servo, establishing a nominal voltage, on an integration capacitor, that is scaled to the reference. This method is used in Figure 2, where the reference level has
3.3F RTH
10
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5V Supply Monitor
5V VL VH 487k 5 VS 1 3 +INA OUTA LT6700-1 4 40.2k -INB OUTB GND 2 6 0.1F
6700123 F01
W
UU
33k
6.04k
VOUT HIGH = (4.7V < VS < 5.3V)
0.1F 2 * VREF RSET 499k 5 VS 3 1 +INA OUTA LT6700-1 4 T 499k -INB OUTB GND 2
6700123 F02
1.4V TO 18V (IS 10A) 220k 220k* T < TSET
6 10k 3.3F
RTH = 1M (e.g., YSI 44015, 1.00M AT 25C) RSET = RTH AT TSET *RESISTANCE MAY REQUIRE OPTIMIZATION FOR OPERATION OVER INTENDED RTH AND VSUPPLY RANGES HYSTERESIS ZONE 0.4C
Figure 2. Micropower Thermostat/Temperature Alarm
been doubled to drive a resistor bridge. The section B output cycles on and off to swing the section B input between its hysteresis trip points as the load capacitor charges and discharges in a shallow, controlled fashion. The multiplied reference signal also contains ripple that is the hysteresis multiplied by the same factor, so additional filtering is performed at the sense node of the bridge to prevent comparator chatter in the section A comparator, which is performing the actual conditional decision for the circuit. Instrumentation Grade Pulse Width Modulator (PWM) Comparators with hysteresis are frequently employed to make simple oscillator structures, and the LT6700 lends itself nicely to forming a charge-balancing PWM function. The circuit shown in Figure 3 forms a PWM that is intended to transmit an isolated representation of a voltage differ6700123fb
LT6700-1/LT6700-2/LT6700-3
APPLICATIO S I FOR ATIO
ence, rather like an isolated instrumentation amplifier. The section B comparator is used to generate a 2V reference supply level for the CMOS NOT gate (inverter), which serves as the precision switch element for the charge balancer. The heart of the charge balancer is the section A comparator, which is detecting slight charge or discharge states on the 0.22F "integration" capacitor as it remains balanced at 400mV by feedback through the NOT gate. The input sense voltage, VIN, is converted to an imbalance current that the NOT gate duty cycle is continually correcting for, thus the digital waveform at the section A comparator output is a PWM representation of VIN with respect
APPLICATIO S I FOR ATIO
10k** 5 * VREF = 2V 22F NC7S14 309k*
+
VIN 0V TO 2V
309k* 0.22F 100k*
-
*1% METAL FILM **DELETE FOR PWM MODE CONNECT FOR PWM MODE OPTIMIZED FOR 2kHz SAMPLING, fPWM(MAX) 0.6kHz
Figure 3. Isolated PWM or Converter
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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to the 2V "full scale." In this particular circuit, the PWM information drives the LED of an optocoupler, allowing the VIN information to be coupled across a dielectric barrier. As an additional option to the circuit, the feedback loop can be broken and a second optocoupler employed to provide the charge balance management. This configuration allows for clocking the comparator output (externally to this circuit) and providing synchronous feedback such that a simple voltage-to-frequency conversion can be formed if desired. Approximately 11-bit accuracy and noise performance was observed in a one second integration period for duty factors from 1% to 99%.
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W W
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3V NOM (IS < 3mA) Lithium COIN CELL 470 412k* 3 5 VS 1 +INA OUTA LT6700-1 4 100k* -INB OUTB GND 2 6 10k 0.1F 6 10k 10k
3V/5V 10k
+
0.1F
750 1 6
PWM OUT (OR SENSE) MOC-207
2
5 3V/5V 750** 1 MOC-207**
6700123 F03
5
2 SAMPLE IN
6700123fb
11
LT6700-1/LT6700-2/LT6700-3
PACKAGE DESCRIPTIO
0.62 MAX
0.95 REF
1.22 REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX 2.62 REF
1.4 MIN
RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR
0.20 BSC 1.00 MAX
DATUM `A'
0.30 - 0.50 REF
TYPICAL APPLICATIO S
PowerPathTM Controller
B0520LW "WART" INPUT 3.3V NOM Si2301DS 10k LED OFF 1k 1M 1M 5 3 VS 1 +INA OUTA LT6700-3 4 R2 150k R1 249k +INB OUTB GND 2 6 1F
6700123 TA04
100k
+
ALKALINE AA CELLS
+
R1 = 400k/(VBATT AT LOW - 0.4) R2 = 400k/(VBATT AT MAX - 0.4) HYSTERESIS ZONES APPROXIMATELY 2% OF TRIP VOLTAGE PowerPath IS A TRADEMARK OF LINEAR TECHNOLOGY CORPORATION
RELATED PARTS
PART NUMBER LT1017/LT1018 LTC1441/LTC1442 LTC1998 DESCRIPTION Micropower Dual Comparator Micropower Dual Comparator with 1% Reference Micropower Comparator for Battery Monitoring COMMENTS 1.1V (Min) Supply Voltage, 1.4mV (Max) Input Offset 1.182 1% Reference, 10mV (Max) Input Offset 2.5A Typ Supply Current, Adjustable Threshold and Hysteresis
6700123fb LT/TP 0104 1K * PRINTED IN USA
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
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S6 Package 6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC (NOTE 4)
2.80 BSC
1.50 - 1.75 (NOTE 4)
PIN ONE ID
0.95 BSC
0.30 - 0.45 6 PLCS (NOTE 3)
0.80 - 0.90 0.01 - 0.10
0.09 - 0.20 (NOTE 3)
1.90 BSC
S6 TSOT-23 0302
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48V Status Monitor
VSUPPLY 1.6V MIN 3V NOM VL VH VIN VIN VWART > 3.1V VBATT > 2V HYSTERESIS ZONES APPROXIMATELY 2% OF TRIP VOLTAGE 10k 5.1V CMPZ5231B 2
6700123 TA03
+
33k 1.74M 3 7.87k 4 LED ON 5 VS 1 +INA OUTA LT6700-1 -INB OUTB GND 6 1 6 27k 22V CMPZ5251B 3V/5V 33k VOUT LOW = (39V < VIN < 70V) MOC-207 5
VOUT
2 0.1F
-
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2003

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